I've been saying it from jump: Biden not winning this thing, stop crying about his poll numbers. He's tanking in multiple polls, he has no campaign infrastructure in Iowa/NH, and he's not doing well enough with young voters.
I think he will drop out after Nevada, ie after losing 4 straight contests. His best shot is in SC where there's a large black population but I think the black vote will shift after someone else becomes the front runner. The black vote basically floods to the front runner. When Kerry started winning primaries, he received the black vote. After Obama win Iowa, the black vote flocked to him. Wouldn't be stunned if Obama's camp leaks a story to the NYT/WaPo before SC about how Obama has spoken to Biden and told him it's over, to deflate his performance.